1. Field of the Invention
This invention relates to compositions and processes for cleaning engineering plastic surfaces. Surfaces that can be effectively cleaned according to this invention include, but are not limited to, polyester sheet molding compound ("SMC"); poly{vinyl chloride} ("PVC") homopolymers and copolymers; polyurethane and polyurea plastic surfaces such as those of objects made commercially by injection molding from these plastics; terpolymers of acrylonitrile, butadiene, and styrene ("ABS"); poly{phenylene oxide} ("PPO") and copolymers of "phenylene oxide" with other materials such as polyamides; polycarbonate ("PCO") polymers and copolymers; and thermoplastic polyolefins ("TPO"). The invention is particularly suited to cleaning plastics, more particularly SMC, that contain solid filler materials, especially those that are chemically alkaline, such as calcium carbonate. Common commercially available types of such SMC materials include PHASE ALPHA.TM. from Ashland Chemical Co., SL 1223.TM. from Eagle Picher Co., Type 7113.TM. from Gencorp, and RI 9486.TM. from Rockwell International, Inc.
The compositions of the invention are substantially or entirely free from phosphate and can be substantially or entirely free from volatile organic solvents as well, and are therefore less polluting than the now common commercial acidic cleaners for plastics.
2. Statement of Related Art and Object of the Invention
Numerous compositions and processes for cleaning plastic surfaces are currently known in the art. Most of them include acid, surfactant(s), and phosphates. In some locations, however, phosphates are forbidden or severely limited to avoid potential pollution and eutrophication of bodies of water that receive discharges of industrial waste water. Thus, compositions that contain little or no phosphate but are still effective cleaners have been sought.